A man who had been bitten by a dog went about in quest of someonewho might heal him. A friend, meeting him and learning what hewanted, said, "If you would be cured, take a piece of bread, anddip it in the blood from your wound, and go and give it to thedog that bit you." The man who had been bitten laughed at thisadvice and said, "Why? if I should do so, it would be as if ishould beg every dog in the town to bite me." 
Benefits bestowed1 upon the evil-disposed increase their  means of injuring you. 